Apparatus suppressing acoustic echo signals from a near-end input signal by estimated-echo signals and a method therefor

Abstract

In an echo suppressing apparatus suppressing from a near-end input signal acoustic echo signals caused by a far-end signal, an estimated-echo path characteristic is multiplied by a far-end signal to produce an estimated-echo signal for each frame, and frames of the estimated-echo signals thus obtained are stored in an estimated-echo signal storage. A delay amount estimator calculates the total of differences between the near-end input signal and each estimated-echo signal thus stored, and determines the amount of frame delay having its total of differences minimal. A delay estimated-echo signal calculator uses the amount of frame delay to read out an optimum frame and near frames respectively preceding and following the optimum frame and to calculate a corrected, delay estimated-echo signal. An echo suppressor uses the estimated-echo signal thus corrected to suppress the acoustic echo signals from the near-end input signal.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an echo-suppressing apparatus, and more particularly to an echo-suppressing apparatus applicable to video teleconference systems and telephone conference systems. The present invention also relates to a method in an echo-suppressing apparatus.[0003]2. Description of the Background Art[0004]For example, in conventional loudspeaker-assisted conference systems such as a video conference system or telephone conference system, there may arise acoustic echo signals caused by part of sound, including acoustic effects and voices, which has radiated from loudspeakers to be caught by microphones to return to the talker. Since acoustic echo signals may severely hinder the quality of telephonic speech, many researches and developments have been heretofore conducted to work out solutions for suppressing such acoustic echo signals.[0005]Conventionally, one of the solutions for suppressing acoustic ech...

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Benefits of technology

[0021]According to the present invention, it is possible to provide an echo-suppressing apparatus which makes interframe corrections by using plural frames of estimated-echo signal to correct an estimated-echo signal, and which stably suppresses acoustic echo signals independently of the amount of delay or frame-by-frame processing.

Problems solved by technology

However, if the echo-suppressing apparatus of C. Faller et al., is used with a telephonic device, such as a softphone or smart phone, having a buffer in its input / output section, the acoustic echo signal may not be suppressed for the following reason.

If the load on the processing becomes increasing, some of the operations may halt processing such as storing or reading out sound data in or from the buffer, thus causing the delay in speech transmission to be increased and thus fluctuant.

In practice, however, the amount of delay may fluctuate because of the echo path characteristic, on the near-end side, and the buffer of the input / output section, thus making it difficult to convert the time domain to the frequency domain at the coinciding timing.

In this way, the echo-suppressing apparatus of C. Faller et al., when used with a device having a possibility of large amount of delay extensively fluctuating, would cause the flame-by-flame processing to influence the shift of the valleys in frequency characteristic between the acoustic echo signal and estimated-echo signal.

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